Congested more with neti pot use?

I have had bad allergies my whole life. I saw the neti pot on Oprah years ago but never got one. I hear that it works great so I finally broke down and got one yesterday. I have used it 3 times now and after each time I actually get more congested and sneeze more. I am using the packets it comes with and luke warm tap water from my sink. I'm wondering if it's something in the packets that I'm allergic to. Has anyone else had this problem? Will my body get use to it and go away after a few uses? I hear all the great stories of the neti pot but I'm not experiencing them. Please help... Thanks!